Temperature – limiting factor [autosaved] new

Temperature – A limiting factor for the
growth of living organisms
Presented By- Sumer Pankaj
Class- M.Sc. EST
Semester- 1
Year – 2016-17
18-07-2016Temperature - A limiting factor to liiving organisms.
1

Outline
 Temperature as a limiting factor.
 Effect of the temperature on plant and
animal life.
 Variation of temperature and its effect
on distribution of plants.
 Altitudinal zonation of vegetation.
 Thermal stratification in atmosphere.
 Thermal stratification in aquatic
ecosystem.
 Effect of temperature on distribution
of animals.
 Adaptations in response to extreme
temperature.
2

Temperature - A limiting factor
 Temperature is the degree or intensity of
heat or coldness present in a substance,
object or an organism. It can be
measured using a thermometer on a
Fahrenheit, Celsius and Kelvin scales.
 Temperature shows temporal as well as
spatial variations resulting in seasonal
variations. It varies according to Latitude
and altitude of earths surface.
 After light, temperature is one of the
major limiting factors, as it limits the
growth of plants, animals, humans and
micro-organisms.
 Maximum and minimum temperature
affects the life of all the organisms on
Earth. 18-07-2016Temperature - A limiting factor to liiving organisms.
3

Effects of temperature on Plants and
animals
 Effect on metabolism
 Effect on reproduction
 Effect on fecundity
 Effect on Growth and Development
 Effect on crossing over
 Effect on sex-ratio
 Effect on colouration
 Effect on morphology
4

Effect on Metabolism
 All metabolic processes are influenced
by temperature and regulates the activity
of enzymes.
 Chemical reactions in the body of
organism are controlled by the
temperature.
 It affects the rate of photosynthesis,
transpiration, respiration rate and
metabolic rate and in both plants and
animals.
 Increase in temperature results in
increase of kinetic energy of molecule,
as a result the subtract molecule collides
with enzyme at faster rate, thus,
increasing the rate of reaction.
5

Effect on reproduction
 Flowering of the plants Is affected by
temperature through Thermoperiodsm (the
response of plant to rhythmic diurnal
fluctuation in temperature). It also plays an
important role in Phenology of plants. (study
of periodical phenomena of plants with
relation to climate).
 In animals maturation of gonads or sex cells
are affected by the temperature. E.g. in blow-
fly the number of eggs laid per female,
increases with the increase in temperature up
to 32ºC.
 Fecundity is the reproductive capacity of the
animal which is affected by the temperature.
E.g. Grasshoppers produce 20-30 time more
eggs at 32ºC than those at 22ºC.
1. Germination of seed
2. Growth
3.Reproduction/
fertilization
4. Flowering
5. Fruiting
6. Seeding
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Effect on growth and development
 Both extremely low and high temperature
have adverse effect on growth of plants as
low temperature brings about such cold
injuries like desiccation, chilling injury
and freezing injury.
 Extremely high temperature causes
stunned growth of the plant due to adverse
effect on processes like respiration,
transpiration rate, and protein metabolism.
 In animals temperature affects the growth
and development. For e.g.:- In oysters the
length of the body increases from 1.5mm
to 10.3mm with increase in temperature
from 10ºC to 20ºC.
Temperature (ºC) Time (hrs.) taken in
hatching of eggs
8 No development
10 207
12 150
15 105
18 70
20 60
21 51
24 No development
Table1:- Effect of temperature on development of
eggs in mackerel
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Effect on crossing over
 In animals like fruit fly Drosophila sp. temperature is
shown to affect the crossing over and somatic expression
of gene characters.
 For e.g. in larval or pupae stage wings tend to be longer at
high temperature and shorter at low temperature.
FACTS
 Thomas Hunt Morgan was an American evolutionary
biologist, geneticist,embryologist, and science author who won
the Nobel Prize in Physiology or Medicine in 1933 for discoveries
elucidating the role that the chromosome plays in heredity.
 The fruit fly is a species of the common housefly known as
Drosophila melanogaster and is distinguished by its red eyes
(dark-colored in some species) tan thorax and black abdomen.
They get their name because of their strong attraction to ripening
or rotting fruit, which serves as a food source as well as a place to
lay their eggs. 18-07-2016Temperature - A limiting factor to liiving organisms.
8

Effect on sex-ratio
 In animals like rotifers and daphnids, sex-ratio
is affected by temperature.
 Under normal conditions daphnids give
parthenogenetic eggs that develop into females,
whereas with increase in temperature they give
sexual eggs which after fertilization develops
into either male or female. Fig:- Female daphnids Fig:- Male daphnids
Fig:- Rotifers
FACT
 The 1,500 to 2,000 species in the phylum Rotifera, like other
members of the kingdom Animalia, are multicellular,
heterotrophic (dependent on other organisms for nutrients),
and lack cell walls. But rotifers possess a unique combination
of traits that distinguish them from other animals,
including bilateral symmetry and a pseudocoelom , a fluid-
filled body cavity between two different layers of embryonic
tissue. The pseudocoelom serves as a sort of circulatory system
and provides space for a complete digestive tract and organs.
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Effect on colouration
 Some insects, birds, and mammals in
warm humid climates bear darker
pigment than the races of same species
present in cool and dry climate. This
phenomena is know as Gloger rule.
 This colouration is because of the
melamine pigment present in the skin, as
the temperature increases the melamine
pigment also increases, thus, the
organisms on the tropical and temperate
regions appear dark in colour as
compared to organisms present at poles.
Exception
 In the frog Hyla and the horned toad
low temperature induced darkening.
Fig:- Honed toad
Fig:- Hyla
10

Effect on morphology
 Temperature affects the absolute size of the animal
and relative proportions of various body parts –
Bargman’s rule. For e.g. birds and mammals
attain greater body size in cold regions than in
warm areas.
 Poikilotherms are smaller in colder areas. There
snout, tail, ear and legs are comparatively shorter
in colder parts than in the warmer areas – Allen’s
rule. For e.g. ear size in artic fox and desert fox.
 Birds having relatively narrow and acuminate
wings tend to occur in colder regions, while in
warmer areas tend to be broader – Rensch’s rule.
 Temperature also affects the morphology of fishes
and is found to have some relatioships with the
number of vertebrate – Jordon’s rule.
Fig:- Arctic fox Fig:- Desert fox
Fig:- birds with broader wings at
warmer areas
Fig:- Birds with narrower wings at
colder areas
11

Variation of temperature
 Temperature shows pronounced temporal
as well as spatial variation. Especially in
tropical and sub-tropical countries seasonal
changers are determined by temperature
fluctuations.
 Temperature values are maximum at
tropical regions and minimum at poles.
This affects a lot of biological diversity.
 Generally temperature is governed by light
intensity, latitude and altitude.
FACT
 For each degree rise in altitude from equator
there is about 10ºF decrease of air
temperature
12

Altitudinal Zonation of vegetation
 On mountains temperature and rainfall are
the major governing factors of vegetation
but G.S. Puri has shown that including these
two factors soil character sticks are also the
important factor.
 At higher elevations, generally temperature
decreases and rainfall increases which
results in the increase of organic matter in
the soil with high amount of nitrogen in soil
and low pH.
 The successive zones of vegetation from
base upwards are- tropical, sub-tropical,
temperate and alpine.
 There are no such sharp boundaries
between the zones, it has been divided on
the basis of different topography, soil and
geology.
13

On basis of temperature conditions scientists have divided the world’s vegetation into
various classes:-
• Areas where low
temperature prevails
throughout the year
and dominant
vegetation is mixed
coniferous type
forest
• Areas where very low
throughout the year
and dominant
vegetation Is alpine.
• Areas where high
alternating with low
temperature, and
dominant vegetation is
tropical deciduous
forest
• Areas where high
throughout the year
and dominant
vegetation is tropical
rain forest
Megatherms Mesotherms
MicrothermsHeskistotherms
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Thermal stratification in atmosphere
 The lapse rate is defined as the rate at which
atmospheric temperature decreases with an
increase in altitude.
15

Thermal stratification in aquatic ecosystems
 In aquatic habitats submerged forms
experience lesser fluctuation of
temperature in the water.
 Larger water bodies due to its high
latent dose not become so cool at
night time followed by mixing of
wind with the water current lessens
the local cooling and heating effects.
 Thus, diurnal variations in
temperature are not much
pronounced in larger water bodies.
16

Thermal stratification in freshwater
ecosystems
 In small ponds diurnal variations may be
pronounced. In deep waters of lakes thermal
stratification may be observed in summers.
 During summers the atmospheric temperature
reaches up to 27ºC, which raise the temperature
of upper layers of water to 22º-23ºC, whereas that
of bottom layers it is as low as only 5ºC.
FACT
 Within the littoral zone producers are of two main types:
rooted or benthic plants, and phytoplankton, floating green
plants, which are mostly algae. Also consist of some weak-
swimming species of Daphia and Simocephalus. The
community of the limnetic zone is composed only of
plankton, nekton, and sometimes neuston (organisms resting
or swimming on the surface). The community comprises of
Blood worms, or haemoglobin containing chironomid larvae
and annelids,Small clams, and Phantom larvae, or Chaoborus
(corethra). 18-07-2016Temperature - A limiting factor to liiving organisms.
17

Zonation of vegetation in aquatic
ecosystem
Epilimnion
Vertical gradient of gradually decreasing
temperature from the surface.
Thermocline or Metalimnion
A short zone of rapid falling temperature.
Hypolimnion
Bottom cold zone where no temperature
gradient is evident.
18

Effect of temperature on distribution of
animals
 On the basis of effect of temperature all the animals are broadly classified into two groups.
- These animals like birds
and mammals are able to
maintain their body
temperature at a constant
level irrespective of the
environmental temperature.
- These animals can
regulate there body
temperature thus they are
also called as warm-
blooded animals.
Hoemothermic
Or
Endothermic
- These are animals like
reptiles, fishes, amphibians
in which the body
temperature fluctuates with
changes in environmental
temperature.
- These animals cannot
regulate there body
temperature thus they are
also called as cold-blooded
animals.
Poikilothermic
Or
ectothermic
19

Thermoregulation in Homoiotherms
 In homoiotherms the most important role is played by their skin.
Response
to cold
Fat serves as
insulator layer.
Hairs gets
raised to
vertical
position.
Contraction of
superficial
blood vessel.
Increase in
metabolic rates.
20

Less fat
deposition.
Hairs flat on skin
surface.
Dilated superficial
blood vessels.
More sweat
glands.
Low metabolic
rate.
Response to
heat
Fact
 In mammals hypothalamic centre act as a thermostat. It is
sensitive to temperature changes of blood flowing through the and
responding by sending nerve impulse through efferent nerves to
appropriate receptors.
 If the temperature of the blood stream is slightly higher than it
should be then hypothalamic centre detects the this and sets into
motion process that collectively encourage the heat loss from the
body.
21

Thermoregulation in Poikilotherms
 Some poikilotherms undergo diapause (a state of
dormancy and arrest growth) to avoid both heat
and cold. E.g. during high temperature
amphibians and turtles burry themselves in the
pond mud, snake and lizard seek burrows.
Exceptions
 During lower temperatures insects like hawk-
moths increases there body temperature from 32º-
36ºC by vibrating its wings before take off.
 During low temperature lizards bask in the sun to
achieve more temperature. Reptiles and frogs
lower there body temperature by evaporating
cooling through skin or respiratory tract.
 Coral reef require minimum temperature of 21ºC
for their suitable growth and are absent in colder
regions. 18-07-2016Temperature - A limiting factor to liiving organisms.
22

Adaptations in response to extremes of
temperature
 During the course of evolution plants and animals
have adopted a number of morphological and
physiological character sticks to survive in
extreme high and low temperature.
 Production of spores, cysts, eggs, pupa, seeds:-
To resist extreme temperature plants and animals
produce thick-walled structures like cysts, spores,
pupa, eggs, seed etc. E.g. Amoeba in encysted
state may tolerate a temperature of 0ºC.
 Increase in the osmotic concentration:-
Increase in the osmotic concentration prevents
freezing. Increase in the osmotic values enhance
the amount of bound water in colloidal form. E.g.
in winters rye at 0ºC, leaves and stem are
flexible, but not brittle.
23

 Removal of water molecule:- Dried seed, cyst,
and spores avoid freezing because no liquid is
present in them to freeze. E.g. Dry seeds are able to
germinate even after their exposure to -190ºC for a
period of 3 weeks.
 Dormancy:- This includes both hibernation and
aestivation.
 Homoiothermy:- Birds and mammals are able to
maintain a constant body temperature irrespective
of the external environmental temperature by
evaporation of water in summers and through
insulating actions like fur, fats in winters.
24

 Thermal migration:- The journey taken
by the animals that enable them to escape
from extremely hot or cold situations are
referred to as thermal migration. It
majorly occurs in fishes, mammals, birds
and desert amphibians.
 Phenotypic changes:- Temperature
affects the phenotype of the animals such
as in Drosophilla melanogaster
temperature affects the development of
eyes and number of legs.
 Similarly in Daphnia body undergoes
different modifications with relation to
seasonal changes in temperature. This
phenomena is known as cyclomorphosis.
E.g. During winter season the head of the
animal is round and it converts into a
helmet like structure during springs and
this attains its maximum size during
summer season and during next winter
the head becomes round again.
25

There is nothing constant on
this planet, we must understand
and act according to it.
THANK YOU
26

Question Bank (MCQ’s)
 The response of plant to rhythmic diurnal fluctuation in temperature is called as:-
(a) Photoperiodism (b) Thermoperiodism (c) Both (a) and (b)(d) None of these.
 In winters the tissues f plants gets dehydrated and injured due to rapid transpiration and
slow absorption, this state is known as:-
(a) chilling injury (b) freezing injury (c) desiccation (d) cold resistance.
 Variation of temperature occurs due to change in:-
(a) Altitude (b) latitude (c) light intensity (d) All of these
 Animals who can maintain their body temperature at constant level irrespective of the external
environmental temperature are known as:-
(a) Hoemotherms (b) poikilottherms (c) cold-blooded animals (d) ectotherms
 A stage during which morphological growth and development remain suspended is known as :-
(a) Hibernation (b) aestivation (c) Diapause (d) None of these
27

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